San Juan-Rak Camel Quarries (Neogene of the United States)

Where: Rio Arriba County, New Mexico (36.5° N, 107.0° W: paleocoordinates 36.9° N, 105.3° W)

• coordinate based on political unit

When: upper tuffaceous zone Member (Chamita Formation), Hemphillian (10.3 - 4.9 Ma)

Environment/lithology: terrestrial

Primary reference: B. J. MacFadden. 1977. Magnetic polarity stratigraphy of the Chamita Formation stratotype (Mio-Pliocene) of North-central New Mexico. American Journal of Science 200 [J. Alroy/J. Alroy/J. Ju]more details

PaleoDB collection 19533: authorized by John Alroy, entered by John Alroy on 27.09.1993

Creative Commons license: CC BY (attribution)

Taxonomic list

• same level as Osbornoceros Quarry
upper tuffaceous zone dated by McIntosh and Quade 1995 using SCLF Ar/Ar on sanidine at between 6.93 +/- 0.05 Ma (base) and 6.78 +/- 0.03 Ma (top); this replaces older FT date on zircon of 5.6 +/- 0.9 Ma for an ash 35 m above the quarries; paleomag correlation is said by MacFadden to be with lowest reversed in the Gilbert, but this matches the banding pattern and new dates poorly, and both McIntosh and Quade 1995 and Lindsay et al. 1984 correlate it with upper "VI" reversed, i.e., 3Ar of Cande and Kent 1992
dates of Dethier et al. 1986 for the Chamita Fm. are for the base of the Fm.
Gomphotherium sp. and Hemiauchenia cf. vera from "6.93" Ma level of Latorre et al. 1997 may pertain to these quarries
Pliometanastes sp. Hirschfeld and Webb 1968: "Santa Clara Canyon" stratigraphically between San Juan and Leyden quarries (relative order not indicated)
"Vulpes stenognathus" is listed by MacFadden et al. 1979 but not discussed; this could be a typographical error

"Osbornoceros osborni" appears to be from the Osbornoceros Quarry of Tedford and Barghoorn 1993 (see); however, Frick 1937 lists this species from "W. Rio Grande, above San Juan"

"Ilingoceros alexandrae" is apparently the same record said by Tedford and Barghoorn 1993 to be from an indeterminate level in the Fm.
Mammalia
 Glires -
 Rodentia - Castoridae
"Dipoides" williamsi Stirton 1936 beaver
 Rodentia - Mylagaulidae
Mylagaulidae indet.1 Cope 1881 rodent
 Lagomorpha - Leporidae
Hypolagus gidleyi5 White 1988 rabbit
 Perissodactyla - Rhinocerotidae
Teleoceras sp.3 Hatcher 1894 rhinoceros
Aphelops mutilus3 Matthew 1924 rhinoceros
 Perissodactyla - Equidae
Dinohippus interpolatus Cope 1893 horse
Astrohippus ansae Matthew and Stirton 1930 horse
 Carnivora - Procyonidae
Procyonidae indet.1 Gray 1825 procyonid carnivore
 Carnivora - Mustelidae
Plesiogulo marshalli2 Martin 1928 mustelid carnivore
Pliotaxidea garberi Wagner 1976 badger
 Carnivora - Canidae
Eucyon davisi1 Merriam 1911 canine
 Ungulata - Camelidae
Megatylopus matthewi Webb 1965 camel
Hemiauchenia sp. Gervais and Ameghino 1880 camel
 Ungulata - Antilocapridae
Antilocaprinae indet.4 Gray 1866 pronghorn
presumably includes "cf. Plioceros sp."; this may be the P. sp. material of Frick 1937 from "W. Rio Grande, above San Juan